It is desirable to prevent contaminants, such as oxygen and carbon dioxide, from entering the components of power generating systems, such as steam generating systems. When the concentrations of oxygen and carbon dioxide are high enough, they become corrodents to iron and steel used in the components of the steam generating systems, including piping and steam generators. The corrosion product is iron oxide, which tends to deposit on steam generator surfaces and reduce heat transfer. Corrosion also causes wall thinning of steel structures in the steam generating systems and can result in leaks and failures. In addition to being a corrodent, carbon dioxide interferes with monitoring of the steam generating systems for more corrosive species, such as chloride. Hence, carbon dioxide is a nuisance that may require the steam generating systems to use more sophisticated monitoring equipment at significantly greater expense.
Despite attempts to prevent the leakage of contaminants into steam generating systems, during certain operating conditions of the steam generating systems, some leakage may occur. For example, contaminants may leak into a condenser of the steam generating system when the system is stopped or slowed, such as during shut-down phase of the system. Various maintenance procedures that may be performed during the system shut-down phase require that one or more of the components of the steam generating system be filled with air, i.e., so that a human may enter into the component to perform maintenance thereto.
After a system shut-down phase and prior to a system start-up phase, condensate polishers may be used to remove contaminants from the condensate e.g., dirt, salts, sodium, chloride, and carbon dioxide that may have leaked into the condenser during a system shut-down phase, which dissolved into the condensate. However, in steam generating systems wherein the temperature of the condensate is above about 60° Celsius, condensate polishers may not be effective to remove many types of contaminants from the condensate, as the effectiveness of condensate polishers at removing some contaminants is reduced at temperatures above about 60° Celsius. The reduced effectiveness is caused by a more rapid degradation of anion resin employed in condensate polishers at temperatures above about 60° Celsius as opposed to significantly slower degradation of the anion resin at temperatures below about 60° Celsius. Further, the effectiveness of condensate polishers at removing silica from condensate is reduced at temperatures above about 50° Celsius.